In a wireless communication system adapted to an LTE scheme or the like, of which specifications have been developed in 3GPP (3rd Generation Partnership Project), a wireless terminal transmits a reference signal to a wireless base station. The wireless base station estimates a state of a transmission path based on the received reference signal and forms antenna directivity for downlink user data.
A method of transmitting a reference signal includes such a method that a wireless terminal transmits a DRS (Demodulation Reference Signal) embedded in uplink user data and such a method that a wireless terminal transmits an SRS (Sounding Reference Signal) by using a part of an UpPTS (uplink part) in a switch subframe or a part of an uplink subframe (for example, a last symbol) (see, for example, PTL 1 (Japanese Patent Laying-Open No. 2010-28192)).